Recently, general brake fluid pressure control devices for a vehicle correspond to not only ABS (Anti-Lock Braking System) but also automatic brake. Such a brake fluid pressure control device is disclosed, for example, in JP-UM-A-2008-143202.
An example of a circuit configuration of a fluid pressure brake device that can execute the automatic brake is shown in FIG. 8. In the drawing, reference symbol MC represents a master cylinder, which accompanies a main reservoir MR that reserves brake fluid at atmospheric pressure. In a service brake, by operating a brake pedal BP, the master cylinder MC is operated to generate brake fluid pressure
The brake fluid pressure generated by the master cylinder MC (hereinafter referred to as “master cylinder pressure”) is supplied to a wheel cylinder WC with passing through a main flow path A to perform the braking. In the main flow path A, an electromagnetic control valve 1 (in the drawing, which is corresponding to a linear electromagnetic valve, and an on/off type cut valve may be used instead of this) having a flow path cutoff function to regulate pressure so that the fluid pressure of the downstream side (the wheel cylinder WC side is considered as the downstream) is increased by a predetermined ratio based on the fluid pressure of the upstream side (master cylinder pressure), and an electromagnetic booster valve 2 are installed.
Further, a decompression path B that passes the brake fluid discharged from the wheel cylinder WC is provided, and an electromagnetic decompression valve 3 and a pressure regulation reservoir 4 are installed in the decompression path B.
In the drawing, a reference symbol 5 represents a pump of which an intake port is connected to the decompression path B, and this pump is driven by a motor 6. A return path C connected to a discharge port of the pump 5 joins between the electromagnetic control valve 1 and the electromagnetic booster valve 2 (a reference symbol cp represents a confluence point).
The pressure regulation reservoir 4 accompanies a pressure response type cut valve 7 that is closed when the brake fluid is introduced, and an intake path D that is connected to the intake port of the pump 5 through the cut valve 7 is provided between the upstream side than the electromagnetic control valve 1 of the main flow path A and the decompression path B. On the other hand, instead of the pressure regulation reservoir 4 accompanying the cut valve 7, an electromagnetic on/off valve (not illustrated) may be incorporated in the intake path D.
Respective parts of the electromagnetic control valve 1, the electromagnetic booster valve 2, and the decompression valve 3, the pressure regulation reservoir 4, the pump 7, and the cut valve 7 are incorporated in a housing (fluid pressure block) 10 to form a pressure regulation unit. One face of the housing 10 is formed as an electromagnetic valve mount face, and parts of components configuring each electromagnetic valve are incorporated in electromagnetic valve mount holes processed on the housing to open the electromagnetic valve mount face. In the drawing, a reference symbol 8 represents a damper that suppresses pulsation of pump discharge pressure, and a reference symbol 9 represents a pressure sensor, which are installed if needed.
Other parts (electromagnetic coil and the like) of the components configuring the electromagnetic valve project to an outside of the housing 10. According to a general brake fluid pressure control device that is configured by combining the pressure regulation unit and an electronic control unit, the projection portion is covered by the case that accommodates a mount board of an electronic control device (ECU), and a motor for driving the pump is attached to a face opposite the electromagnetic valve mount face.
In the illustrated brake device, the electronic control device ECU determines the necessity of pressure regulation of the wheel cylinder pressure based on information from an acceleration sensor, a wheel speed sensor (not illustrated), and the like, which watch the movement of the vehicle. If it is determined that the pressure regulation is necessary, an operating command is sent from the electronic control device ECU to the electromagnetic control valve 1, the electromagnetic booster valve 2, the electromagnetic decompression valve 3, or the motor 6 to regulate the wheel cylinder pressure.
In the automatic brake control, the brake pedal BP is not operated, and the electromagnetic control valve 1 is closed with the start of the control. If the pump 5 is driven in this state, the pump 5 performs an intake of the brake fluid in the main reservoir MR through the intake path D and a pressure chamber of the master cylinder MC (this chamber communicates with the main reservoir MR when the master cylinder is not operated), and then compresses and discharges the brake fluid. The discharge fluid returns to the main flow path A to be supplied to the wheel cylinder WC, and a friction material presses a rotor so that the fluid pressure to generate a braking force.